LS1 Powered S14 by SicBastard

6 minute(s) of a 390 minute read

Here's a pic of some of the sizes of Toyo RA1s I'm considering.



I originally went with the 275/40/17 (d=652mm) Azenis cuz they are about the shortest/widest/cheapest thing I could find. But lookin towards the future, check out those 315/30/18s (d=648mm)! They're even shorter than my 275s! And the 285/30/18s (d=631mm) are the shortest tires on the whole list, even shorter than the 255/40/17s (d=638mm)that I'm runnin on the front right now!

Now there is always a big (seriously, it's not cool) jump in tire cost going from 17s to 18s, so why is it worth it? A big double whammy of lower CG OR better roll centers (given the same ride height).

You have to devide the tires outer diameter by pi to get their height. And swapping my front 255/40/17 (d=652mm) for the wider/shorter 285/30/18s (d=631mm) would lower my tire height 652mm/pi-631mm/pi= 207.54mm-200.85mm = 6.68mm = 0.263"

The spindle is lowered by half the difference of the tire heights. So 0.263"/2 = 0.132". That's a bit more than an eighth of an inch of roll center correction or better CG, just for changing tires from a skinnier 255/17 to the lower profile 285/18!

Of course it would be even sweeter if they made 30 series 17" rubber, or better yet 15" rubber in something wider than a 225. But nobody does. So if you can afford it. Step up to 18s.

2/15/12

I scored $500 of dry sump tank for $135 shipped on ebay! And it even showed up undamaged!



I've been stalking these things forever, but the Nascar surpluss are always 9" or 13" in diameter and usually closer to 4 gallons. This tank is 6"dx21"h and 2.25 gallons. A full gallon bigger than the stock Zo6 tank. That extra 2 gallons in most of the Nascar tanks is 16 lbs and $80/oil change that I don't need. Now I just need to see if I can squeeze that tank in the trunk with my giant 22gallon fuel cell. Cross your fingers for me! The tank is really light at less than 7 lbs dry, but wet it'll be closer to 23lbs. I really don't want that weight in the front of the car. Nor do I want 2+ gallons of 220F oil in the driver compartment, but I may have no choice.

I also got the parts for some of my home-made rear control arms, I'll have a post on those next week.

And in other news, I got engaged, and my homees and I are trying to plan a road-trip/bachelor party from LA, through Vegas, and onto Bonneville for Speedweek! It's August 11-17th this year. I'm hoping the 240 will be done for speedweek 2013. But this year maybe I can make a few licensing runs in a rental!

3/4/12

I was worried that there wouldn't be room for the ATL 22b fuel cell AND the dry sump tank both in the trunk. There actually is room to have both the dry sump tank and my huge fuel cell in the trunk even with the fuel cell centered. For cross weight balance it might be beneficial to have the fuel cell offset a little but then my cross weights will change as fuel is used. I guess that's true even if it's centered! What do you guys think?

Lots of room. On both sides





My DIY toe and traction rods are complete too.



I've been rethinking a few things too. Originally I was going to raise the fuel cell a few inches so that I could start the diffuser at the rear center axle, but now I'm thinking that extra rear downforce is easy to get with a bit more wing, but a lower CG you have to really fight for. So the fuel cell is going to drop a bit, and the diffuser ramp will have to start a little later.

Here's the solution that the famous BRE came up with



that huge thing where the rear passenger side seat used to be is a box to hold the dry sump. Definitely a lower PMOI than my trunk solution, but with corner exit and balance in the sweepers a greater priority in my time attack (not autocross) car, I think the better weight distribution in the trunk is the way to go. Plus it's a little less butchering, and a little less weight.

4/9/12

Anybody going to the NYC auto show this week?

I've spent another 2 days or so working on the rear subframe... Feels like it's never going to end.

In other news I may be replacing my custom/OMP extended shifter with this:

My Uncle goes into surgery later this month for a replacement, and I have first dibs on the old one!